Autonomous Moving Device and Control Method Thereof

ABSTRACT

An autonomous moving device includes a travel unit with a wheel driven by a motor and an upper body including an environment-recognition sensor that detects an obstacle in a traveling direction. The upper body includes means that recognize device and obstacle positions, means that evaluates avoidance capability, and means that obtains priority of collision avoidance of an estimated passage area of the obstacle. The upper body further includes a control unit that moves the travel unit to an area where an estimated passage area of an obstacle whose priority of collision avoidance is high that does not overlap an area where the travel unit is located and which is an area where collision can be avoided even if an area where an estimated passage area of an obstacle whose priority of collision avoidance is low overlaps the area where the travel unit is located.

TECHNICAL FIELD

The present invention relates to an autonomous moving device withobstacle avoidance capability and a control method thereof.

BACKGROUND ART

When an autonomous moving device such as a robot moves in human lifespace, the movement of the autonomous moving device may be an obstaclefor a person in some cases, so that some sort of countermeasure isrequired.

As a background art for such a case, for example, there is JapaneseUnexamined Patent Application Publication No. 2010-79852 (PatentLiterature 1). In Patent Literature 1, while the autonomous movingdevice is moving according to a target position trajectory, even whenthe movement is interrupted by an obstacle, the autonomous moving devicecan recognize the behavior of the obstacle. Further, when the obstacle,which is an object (human being, another autonomous moving device, andthe like) that can autonomously move, moves, if the autonomous movingdevice can move according to a current target position trajectory, theautonomous moving device can control action to urge the obstacle to moveto make way for the autonomous moving device.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2010-79852

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2008-65755

SUMMARY OF INVENTION Technical Problem

If there are plural obstacles that interrupt movement of the autonomousmoving device, each obstacle may have different avoidance capabilitiessuch as acceleration and deceleration capability and a movabledirection.

For example, in a hospital, there is a case in which a passage isblocked by a healthy person, a wheelchair, and a disabled person at thesame time. In this case, the avoidance capability of the wheelchair andthe disabled person is lower than that of the healthy person. Therefore,if the autonomous moving device is located at a position at which theautonomous moving device blocks the way of the wheelchair or thedisabled person, there is a probability that it takes time to pass eachother or the wheelchair or the disabled person accidentally contactswith the autonomous moving device. In this case, if the autonomousmoving device moves in the way of the healthy person whose avoidancecapability is high, the influence on the movement of the wheelchair andthe disable person is small.

However, for example, if the autonomous moving device moves in front ofthe healthy person, there is a probability that the avoidance behaviorof the healthy person takes time or causes accidental contact, so thatit is necessary for the autonomous moving device to move to a positionwhere the healthy person can easily avoid the autonomous moving device.

In order to efficiently and safely cope with a situation in which themovement is blocked by plural obstacles in this way, it is necessary toprovide an autonomous moving device which moves to a position where theinfluence on the movement of the obstacle whose avoidance capability islow is small and where and the obstacle whose avoidance capability ishigh can easily avoid the autonomous moving device. However, thetechnique described in Patent Literature 1 may not be able to safelycope with the situation because the technique does not consider the casein which the autonomous moving device confronts plural obstacles.

An object of the present invention is to provide an autonomous movingdevice which, when there are plural obstacles that block the movement ofthe autonomous moving device, can move to a position where the influenceon the movement of the obstacle whose avoidance capability is low issmall and where the obstacle whose avoidance capability is high caneasily avoid the autonomous moving device.

Solution to Problem

The above object can be achieved by an autonomous moving deviceincluding a travel unit including a wheel driven by a motor and an upperbody including an environment recognition sensor that detects anobstacle in a traveling direction. In the autonomous moving device, theupper body includes a means for recognizing a position of the autonomousmoving device and an obstacle, a means for evaluating avoidancecapability of the obstacle, a means for determining capability ofavoidance of collision with the obstacle, and a means for obtainingpriority of collision avoidance of an estimated passage area of theobstacle from the capability of avoidance of collision, and the upperbody further includes a control unit that moves the travel unit to arange which is an area where an estimated passage area of an obstaclewhose priority of collision avoidance is high does not overlap an areawhere the travel unit is located and which is an area where collisioncan be avoided even if an area where an estimated passage area of anobstacle whose priority of collision avoidance is low overlaps the areawhere the travel unit is located.

To achieve the above object, it is preferable that the means forevaluating avoidance capability quantitatively calculates the avoidancecapability from a velocity and a width of the obstacle.

To achieve the above object, it is preferable that the means forevaluating avoidance capability sets avoidance priority of the obstaclewhose avoidance capability is lower than a reference value to be high.

To achieve the above object, it is preferable that the means forevaluating avoidance capability sets avoidance priority of an obstaclewhose velocity is slower than a reference range and an obstacle whosevelocity is faster than the reference range to be high.

To achieve the above object, it is preferable that the means forevaluating avoidance capability classifies the obstacle into severaltypes on the basis of avoidance capability.

The above object can be achieved by a control method of an autonomousmoving device including a communication device that communicates with acomputer including an information storage unit, a travel informationcalculation unit, an obstacle recognition unit, a travel control unit,an obstacle classification unit, a destination point setting unit, andan action determination unit. The control method includes a step ofdetermining the presence or absence of information from the obstacleclassification unit. a step of transmitting a final destination point inthe information storage unit to the travel control unit as a currentdestination point when no information is transmitted from the obstacleclassification unit, a step of obtaining a passable area in which theautonomous moving device can travel without colliding with an obstacleby a travel unit when information is transmitted from the obstacleclassification unit, a step of estimating a passage area of a currentlycaptured obstacle, a step of setting a virtual passable area which is anarea virtually set to be passable for the sake of calculation, and astep of determining a destination point based on the virtual passablearea.

Advantageous Effects of Invention

According to the present invention, it is possible to provide anautonomous moving device which, when there are plural obstacles thatblock the movement of the autonomous moving device, can move to aposition where the influence on the movement of the obstacle whoseavoidance capability is low is small and where the obstacle whoseavoidance capability is high can easily avoid the autonomous movingdevice.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram showing movement of an autonomous movingdevice according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the autonomous movingdevice according to the first embodiment.

FIG. 3 is a diagram for explaining a classification method of obstaclesaccording to the first embodiment.

FIG. 4 is an operation flowchart of a destination point determinationunit according to the first embodiment.

FIG. 5 is a diagram for explaining a passable area according to thefirst embodiment.

FIG. 6 is a setting method of an obstacle passage area according to thefirst embodiment.

FIG. 7 is a diagram for explaining a virtual passable area according tothe first embodiment.

FIG. 8 is a diagram for explaining a determination method of adestination point TG according to the first embodiment.

FIG. 9 is a movement example of a case in which the obstacles are onlyclass A according to the first embodiment.

FIG. 10 is a movement example of a case in which the obstacles are onlyclass B according to the first embodiment.

FIG. 11 is a movement example of a case in which the obstacles are onlyclass C according to the first embodiment.

FIG. 12 is a configuration diagram of an autonomous moving deviceaccording to a second embodiment.

FIG. 13 is an operation flowchart of the autonomous moving deviceaccording to the second embodiment.

FIG. 14 is a diagram for explaining a determination method of atemporary destination point TG according to the second embodiment.

FIG. 15 is a diagram for explaining a determination method of TG whenthe autonomous moving device cannot pass through a virtual passable areaaccording to the second embodiment.

FIG. 16 is a diagram for explaining a determination method of TGaccording to a third embodiment.

FIG. 17 is a diagram showing a setting example of a passage areaaccording to topographic features according to a fourth embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, multiple embodiments will be described with reference tothe drawings. In the embodiments, the width of passage through which anautonomous moving device passes has a length in which the autonomousmoving device and another obstacle can pass each other at all times.

First Embodiment

The present embodiment will be described with reference to FIGS. 1 to11.

An overview of the autonomous moving device realized by the presentembodiment will be described with reference to FIG. 1.

FIGS. 1( a) to 1(c) are conceptual diagrams showing movement of theautonomous moving device according to the first embodiment of thepresent invention.

In FIG. 1, when the movement of the autonomous moving device 1 isblocked by plural obstacles traveling in a virtual passable area 61 (atravel path), the autonomous moving device 1 evaluates avoidancecapabilities of the obstacles and calculates avoidance priorities.

In the case of FIG. 1( a), the autonomous moving device 1 recognizesthat a disabled person B1 and a wheelchair B2 are obstacles with highavoidance priority because the avoidance capabilities of the disabledperson B1 and the wheelchair B2 are lower than that of a healthy personC1. Areas 51B1 and 51B2 are passage areas through which it is estimatedthat the disabled person B1 and the wheelchair B2 will pass. Theautonomous moving device 1, which estimates the passage areas 51B1 and51B2, avoids the disabled person B1 and the wheelchair B2, which havehigh avoidance priority, and moves to a position which is outside thepassage areas 51B1 and 51B2 and where a required course change of thehealthy person C1, who has low avoidance priority, is small.

In a state of FIG. 1( b), the healthy person C1, who observes theautonomous moving device 1 which changes course to the passage areas ofthe healthy person C1 with low avoidance priority, moves behind thedisabled person B1 and prioritizes the travel of the autonomous movingdevice 1.

In a state of FIG. 1( c), after confirming that there is no obstacle inthe passage area, the autonomous moving device 1 can quickly passthrough by avoiding the disabled person B1 and the wheelchair B2.

Under the situation of FIG. 1( a), a conventional autonomous movingdevice 1 does not evaluate the avoidance capabilities of the obstaclesand does not set the passage area, so that the conventional autonomousmoving device 1 does not completely depart from the passage areas of theobstacles with low avoidance capabilities. Therefore, the disabledperson B1 and the wheelchair B2 with low avoidance capabilities changetheir courses, so that the efficiency may be bad and a risk may occur.

On the other hand, the autonomous moving device 1 of the presentinvention can move to a position where the autonomous moving device 1does not block the way of the obstacles with low avoidance capabilitiesand which the obstacle with high avoidance capability can easily avoid.

FIGS. 2( a) and 2(b) are schematic configuration diagrams of theautonomous moving device according to the first embodiment.

FIG. 2( a) is a mechanical configuration diagram and FIG. 2( b) is asystem configuration diagram of the autonomous moving device 1 accordingto the present embodiment. In the present embodiment, it is assumed thatthe autonomous moving device 1 is smaller than a human being and mainlytravels indoors.

The mechanical configuration of the present invention will be describedwith reference to FIG. 2( a). The autonomous moving device 1 includes atravel unit 11 and an upper body 12. The autonomous moving device 1externally has a computer 2 connected to a communication device 3 andthe autonomous moving device 1 and the computer 2 bi-directionallyexchange information by wireless communication (indicated by arrows)through the communication device 3 and a communication device 124.

The travel unit 11 includes wheels 111 and drive motors 112 with anencoder. The upper body 12 includes a battery 121, which is a powersource of the autonomous moving device, and a control device 122. Theupper body 12 includes a laser scanner as an environment recognitionsensor 123 that detects an obstacle and the communication device 124that communicates with the computer 2. As shown in FIG. 2( b), thecomputer 2 includes an information storage unit 21, a travel informationcalculation unit 22, an obstacle recognition unit 23, a travel controlunit 24, an obstacle classification unit 25, a destination point settingunit 26, and an action determination unit 20.

The system configuration of the present invention will be described withreference to FIG. 2( b). The detailed processes of each component willbe described later.

First, obstacle information acquired from the environment recognitionsensor 123 and wheel turning angle velocity acquired from the travelunit 11 are transmitted to the information storage unit 21 of thecomputer 2 through the communication device 124 included in theautonomous moving device 1 and the communication instrument 3 connectedto the computer 2. The information storage unit 21 store informationnecessary to control the autonomous moving device, such as a finaldestination point inputted from the action determination unit 20,measurement data from the environment recognition sensor 123 and theencoder of the motor 112, the current position, orientation, andvelocity of the autonomous moving device 1 calculated by the travelinformation calculation unit 22, and the current position and velocityof an obstacle calculated by the obstacle recognition unit 23 in amemory of the computer 2 or updates/calls data in the memory.

The final destination point of the action determination unit 20 isinputted by a person from a terminal of the computer 2 or determined bya program in advance. The travel information calculation unit 22calculates the current origin reference coordinates, orientation,forward velocity, and tangential velocity of the autonomous movingdevice 1 from measurement result of the encoder of the motor 112 storedin the information storage unit 21 and returns the current originreference coordinates, orientation, forward velocity, and tangentialvelocity to the information storage unit again. The obstacle recognitionunit 23 estimates the coordinates, velocity, and width of an obstaclefrom measurement result of the environment recognition sensor 123 storedin the information storage unit 21 and returns the coordinates,velocity, and width to the information storage unit 21.

The travel control unit 24 transmits a target forward velocity and atarget tangential velocity to the control device 122 through thecommunication devices 3 and 124 on the basis of obstacle information inthe information storage unit 21 and a current destination point set bythe destination point setting unit 26. Further, the travel control unit24 determines whether the autonomous moving device 1 can avoid theobstacle at all times and if the autonomous moving device 1 cannot avoidthe obstacle, the travel control unit 24 notifies the obstacleclassification unit 25 that the autonomous moving device 1 cannot avoidthe obstacle. When the obstacle classification unit 25 is notified thatthe autonomous moving device 1 cannot avoid the obstacle from the travelcontrol unit 24, the obstacle classification unit 25 classifies theobstacle by avoidance capability, determines avoidance priority order ofthe obstacle, and notifies the destination point setting unit 26 of theavoidance priority order.

When no information is transmitted from the obstacle classification unit25, the destination point setting unit 26 notifies the travel controlunit 24 of the final destination point of the travel information storage21 as a current destination point, and when information is transmittedfrom the obstacle classification unit 25, the destination point settingunit 26 calculates a point at which the autonomous moving body 1 doesnot block the way of an obstacle of high avoidance priority order and atwhich an obstacle with low avoidance priority order can easily avoid theautonomous moving device 1 and notifies the travel control unit 24 ofthe point as a destination point.

Thereafter, the travel control unit 24 re-calculates a straight forwardvelocity and a tangential velocity to advance to the destination pointset by the destination point setting unit 26 while avoiding the obstacleand indicates the straight forward velocity and the tangential velocityto the control device 122 through the communication devices 3 and 124.The control device 122 controls moving direction and moving velocity ofthe travel unit 11 on the basis of information of the velocityindication from the information storage unit 21 and the travel unit 11.

Hereinafter, the details of the calculation process of each componentwill be described.

In the present embodiment, a laser scanner is used as the environmentrecognition sensor 123, and a data string of distances to the obstacleat a predetermined angle interval is transmitted to the informationstorage unit 21 through the communication devices 124 and 3. The encoderof the motor 112 detects the turning angle velocity of the wheel andtransmits the turning angle velocity to the information storage unit 21through the communication devices 124 and 3.

The information storage unit 21 stores an origin which is set by a userwhen starting the autonomous moving body, the coordinates of the finaldestination point with respect to the origin, the obstacle informationand the turning angle velocity of the wheel for the past severalseconds, and the calculation results of the travel informationcalculation unit 22 and the obstacle recognition unit 23 into the memoryof the computer 2.

The travel information calculation unit 22 calculates the current originreference coordinates, orientation, forward velocity, and tangentialvelocity of the autonomous moving device 1 from time history of theturning angle velocity of the wheel and the orientation of theautonomous moving device 1 stored in the information storage unit 21 andreturns the current origin reference coordinates, orientation, forwardvelocity, and tangential velocity to the information storage unit 21again.

The obstacle recognition unit 23 estimates the coordinates, velocity,and width of the obstacle from the data obtained from the environmentrecognition sensor 123 and transmits the coordinates, velocity, andwidth to the information storage unit 21. Although a laser scanner isused in the present embodiment, the obtained data is a data string ofeach predetermined angle interval. Therefore, a recognition method forrecognizing that plural obstacles are separate obstacles is required.

For example, as the recognition method, there is a method of JapaneseUnexamined Patent Application Publication No. 2008-65755.

In this method, first, an abrupt change point of distance valuesobtained from the laser scanner with respect to angle at a certain timet, the data string is divided into groups of continuous points, and thedivided data string is stored as segments in the information storageunit 21. Thereby, feature amounts such as a representative point such asthe center of gravity, a shape, and the like of each segment at the timet are recognized. Next, the same calculation is performed at the timet+Δt and the feature amounts of each segment are obtained.

Here, the feature amounts of the segments obtained at the time t arecompared with the feature amounts of the segments obtained at the timet+Δt, segments whose feature amounts are similar to each other arerecognized to be the same obstacle, the velocity of the obstacle can beobtained from the amount of change of the representative position, andthe width of the obstacle can be obtained from the shape. An obstaclewhose moving velocity is substantially 0 is assumed to be a stationaryobstacle, each data point obtained by the laser scanner is assumed to bean obstacle with a width of 0, and the assumed obstacles are stored inthe information storage unit 21.

In the travel control unit 24, a generally well-known obstacle avoidancemethod “The Dynamic Window Approach to Collision Avoidance.” (IEEERobotics & Automation Magazine 4(1), pp. 23-33, 1997) is used. Thismethod selects pk and vq which maximize G(pk, vq) of an objectivefunction shown by the formula 1 in which a distance-to-obstacle functionLcol(pk, vq) when the autonomous moving device 1 travels at severallevels of target tangential velocity candidates p1, p2, . . . , pk andseveral levels of target forward velocity candidates v1, v2, . . . , vq,at which the autonomous moving device 1 can travel, a directionalfunction θgoal(pk) with respect to destination point coordinatestransmitted from the destination point setting unit, and a forwardvelocity function V(vq) are evaluated and these functions are multipliedby α, β, and γ respectively and summed up.

[Formula 1]

G(pk, vq)=α·Lcol(pk, vq)+β·θgoal(pk)+γ·V(vq)   (Formula 1)

The α, β, and γ can be set by a simulation or an experimental rule. Theselected target tangential velocity pk and target forward velocity vqare transmitted to the control device 122 through the communicationdevices 3 and 124. If only moving destination candidates whose angle θof velocity vector to the destination point is greater than or equal to90° or G(pk, vq) is the maximum when vq≦0, it is determined that it isimpossible to avoid obstacles while approaching the destination pointand an avoidance impossible flag is transmitted to the obstaclerecognition unit 23.

When the obstacle classification unit 25 receives the avoidanceimpossible flag from the travel control unit, the obstacleclassification unit 25 classifies the obstacles by avoidance capabilityfrom the velocity and width of the obstacles stored in the informationstorage unit 21 and determines the avoidance priority order. Theavoidance capability of a healthy pedestrian is assumed to be thehighest. If the width of the obstacle is greater than that of anordinary pedestrian, the obstacle is assumed to be a moving body otherthan a human being and the avoidance capability is assumed to be low. Amoving body whose moving velocity is slower than that of a healthypedestrian is assumed to be a moving body other than a human being, or aperson who carries a heavy thing, or a disabled person. A moving bodywhose moving velocity is faster than that of a healthy pedestrian isassumed to be a moving body whose velocity and course are difficult tobe changed quickly, such as a runner and a bicycle. The avoidancecapabilities of the above moving bodies are assumed to be low. In thepresent embodiment, the avoidance capability of the obstacle isevaluated by using the sum R obtained by summing up the width W and thevelocity V of the obstacle, which are multiplied by weights a and b, andthe obstacles are classified from the R and the width W and the velocityV of the obstacles.

[Formula 2]

R=a·W+b·V   (Formula 2)

The weights a and b are obtained from the upper limit value Rmax of theR of a healthy person described later. The classification method will bedescribed with reference to FIG. 3.

FIG. 3 is a diagram for explaining the classification method of theobstacles according to the first embodiment.

In FIG. 3, when the lower limit velocity of a healthy pedestrian isVmin, the upper limit width of a healthy pedestrian is Wmax, and theupper limit of the R of a healthy pedestrian is Rmax, the obstacle isclassified as described below and the avoidance priority is defined asA>B>C.

[Formula 3]

If R>Rmax, class A

If (V<Vmin and W<Wmax) or (R<Rmax and W>Wmas), class B

If Vmin<V and W<Wmax and R<Rmax, class C   (Formula 3)

The Rmax is heuristically determined so that the obstacles areclassified as shown in FIG. 3. From the Rmax, a and b in the formula 2are determined. A moving body of the class A whose R is great is a wideand heavy moving body or a moving body that moves at a high speed, sothat it is difficult for the moving body to change the velocity andchange the course. Therefore, the autonomous moving device 1 has toactively avoid the moving body. A moving body of the class B whose V andR are small and W is great is a moving body that cannot change thecourse easily but can stop easily because of the size and the lowvelocity thereof, so that it is assumed that the moving body can avoidcollision with the autonomous moving device 1 by stopping itself. Amoving body of the class C has the same avoidance capability as that ofa healthy person because of the velocity and the width, so that it isassumed that the moving body can easily avoid the autonomous movingdevice 1.

The operation of the destination point setting unit 26 will be describedwith reference to FIGS. 5 to 8 on the basis of a flowchart in FIG. 4.

FIG. 4 is an operation flowchart of the destination point determinationunit according to the first embodiment.

In FIG. 4, when no information is transmitted from the obstacleclassification unit 25 in S100, the destination point setting unit 26proceeds to S101. When information is transmitted from the obstacleclassification unit 25 to the destination point setting unit 26, thedestination point setting unit 26 proceeds to S102 and the subsequentsteps, calculates a point TG at which the autonomous moving body 1 doesnot block the way of an obstacle of high avoidance priority order and atwhich an obstacle with low avoidance priority order can easily avoid theautonomous moving device 1, and notifies the travel control unit 24 ofthe point TG as a destination point.

In step 101, the destination point setting unit 26 notifies the travelcontrol unit 24 of the final destination point in the informationstorage unit 21 as the current destination point TG.

In S102, as shown by the shaded area in FIG. 5, a passable area 60 isobtained in which the autonomous moving device 1 can travel withoutcolliding with an obstacle by the travel unit 11. The passable area 60is defined as Pa and the formula 4 is defined from the coordinates Oiand the width Wi of an ith obstacle (i=1, 2, . . . , N) stored in theinformation storage unit 21.

[Formula 4]

Pa={X| ∥X−Oi[>r+Wi}  (Formula 4)

Here, r is a necessary distance for an obstacle to safely avoid thecollision with the autonomous moving device 1 and r is set on the basisof the size of the autonomous moving device 1, a distance between theautonomous moving device 1 and another moving body when the autonomousmoving device 1 and the other moving body pass each other, and adistance between the autonomous moving device 1 and a peripheral objectwhen another component of the autonomous moving device 1 is operated.

In S103, a passage area 51 of a currently captured obstacle isestimated. When the coordinates from the origin of N obstacles Oiobtained from the information storage unit 21 are Oi, the velocityvector is Vi, and the unit normal vector of Vi is ni, the passage areaT(Oi) of the Oi is estimated as the formula 5.

[Formula 5]

T(Oi)=Oi+s·Vi+t·ni, s≧0 and |t|≦Wi/2+r   (Formula 5)

As shown in FIG. 6, when the current position Xi of the autonomousmoving device 1 is substituted for the left term of the formula 5 and sand t are obtained, if the values of s and t satisfy s≧0 and |t|≦Wi/2+r,it is determined that the autonomous moving device 1 is in the passagearea of the obstacle Oi.

In S104, a virtual passable area 61 (shaded area in FIG. 7) is set whichis an area virtually set to be passable for the sake of calculation. Thevirtual passable area 61 is set as described below on the basis of theavoidance priority order set by the obstacle classification unit 25.

-   (1) When the types of N obstacles Ai (i=1, 2, . . . , N) in the    passable area 60 or the virtual passable area 61 are only A, the    passage areas 51Ai of all the obstacles are set to be impassable as    shown in FIG. 7( a) and the remaining area is set to a virtual    passable area 61P. When the coordinates of Ai from the origin are    Oi, the width is Wi, the velocity vector of each obstacle is Vi, and    the unit normal vector of Vi is ni, the virtual passable area 61P is    represented by the formula 6.

[Formula 6]

P={X|X=Oi+s·Vi+t·ni, i is a natural number from 1 to N and (s<0 or|t|>Wi/2+r)}  (Formula 6)

-   (2) When the types of N obstacles Bi (i=1, 2, . . . , N) in the    passable area 60 or the virtual passable area 61 are only B, the    passage areas 51Bi of the obstacles Bi (i≠k) except for an obstacle    Bk whose velocity is the slowest are set to be impassable as shown    in FIG. 7( b) and the remaining area is set to a virtual passable    area 61P (shaded area in FIG. 7( b)).

[Formula 7]

P={X|X=Oi+s·Vi+t·ni, i is a natural number from 1 to N other than k and(s<0 or |t|>Wi/2+r)}  (Formula 7)

As the aforementioned Bk, an obstacle which is the last obstacle to becollided with may be selected.

-   (3) When the types of the obstacles in the passable area 60 or the    virtual passable area 61 are only C, the passable area 60 or the    virtual passable area 61 are used without change.-   (4) When there are at least two types (among A, B, and C) of    obstacles in the passable area 60, the passage areas of all the    obstacles except for obstacles of the type whose avoidance priority    is the lowest are set to be impassable and the remaining area is set    to a virtual passable area 61. As shown in FIG. 7( c-1), when P    obstacles Mi (i=1, 2, . . . , P) are obstacles of the type whose    avoidance priority is the lowest, Q obstacles Nj (j=1, 2, . . . , Q)    are obstacles of the other types, the coordinates of Nj is Nj, the    velocity is Vj, and the unit normal vector of Vj is nj, the virtual    passable area 61P (shaded area in FIG. 7( c-1)) is represented by    the formula 8.

[Formula 8]

P={X|X=Nj+s·Vj+t·nj, j=1, 2, . . . , Q and (s<0 or|t|>Wj/2+r)}  (Formula 8)

The virtual passable area 61 is set as described above, so that theobstacles located in the virtual passable area 61 can be limited to oneof the B and C types. Therefore, by performing (2) or (3) describedabove and updating the virtual passable area, the virtual passable area61 finally becomes as shown in FIG. 7( c-2).

In S105, the destination point TG is determined based on the virtualpassable area 61 set in S104. The determination method of the TG will bedescribed with reference to FIG. 8.

When all the types of the obstacles are the class A, as shown in FIG. 8(a), the travelling direction of the autonomous moving device 1 isblocked by impassable areas. In this case, a point behind the autonomousmoving device 1 and closest to the autonomous moving device 1 in thevirtual passable area is determined as the destination point TG. Whenthe obstacles include an obstacle of a class other than A, by theprocess of (2), (3), or (4) in S104, in the virtual passable area 61,there is only one obstacle of class B or C or there are plural obstaclesof class C.

When there is only one obstacle O5 in the virtual passable area 61 asshown in FIG. 8( b), if the autonomous moving device 1 moves to aboundary line L1 or L2 of the virtual passable area 61, the change ofcourse of the obstacle O5 can be small. To uniquely determine theposition on L1 or L2, for example, the intersection points between astop position 71 when the autonomous moving device 1 decelerates at themaximum acceleration in a possible turning direction and L1 and L2 aredetermined as candidates of the TG. If the distance between theautonomous moving device 1 and L1 is greater than the distance betweenthe center of the autonomous moving device 1 and L2, the intersectionpoint between L1 and the stop position 71 is determined as a temporarydestination point TG, and if it is the other way around, theintersection point between L2 and the stop position 71 is determined asa temporary destination point TG. As show in FIG. 8( c), when there areN obstacles (Oi, i=1, 2, . . . , N) in the virtual passable area 61, ifthe autonomous moving device 1 moves to the boundary lines L1 and L2 ofthe virtual passable area 61 and a median line Lik between boundarylines of passage areas 51Oi and 51Ok of obstacles Oi and Ok (k=1, 2, . .. , N, |i−k|=1) adjacent to each other, the changes of courses of theobstacles are small, so that, in the same manner as in the case in whichthere is one obstacle, a point at which the distance between theboundary of the passage area of the obstacle and the autonomous movingdevice 1 is the greatest is determined as the temporary destinationpoint TG from among the intersection points between the stop position 71and each of L3, L4, and Lik).

The control device 122 controls the motor 112 of the travel unit 11 sothat the forward velocity and the tangential velocity of the autonomousmoving device 1 are performed as instructed by the travel control unit24.

Hereinafter, an operation example of the autonomous moving device 1 willbe described with reference to FIGS. 1, 9, 10, and 11.

In these drawings, to easily understand the concept, r in the formulas 4to 8 is set to 0, and instead an area 72 occupied by the autonomousmoving body 1 is represented by a circle whose radius is r and center isthe position of the autonomous moving device.

FIG. 9 is a movement example of a case in which the obstacles are onlyclass A according to the first embodiment.

FIG. 10 is a movement example of a case in which the obstacles are onlyclass B according to the first embodiment.

FIG. 11 is a movement example of a case in which the obstacles are onlyclass C according to the first embodiment.

FIG. 1 is an example of a case in which the movement of the autonomousmoving device 1 is blocked by plural obstacles.

For example, the healthy person C1 is classified to the class C and thedisabled person B1 and the wheelchair B2 are classified to the class B.The healthy person C1 of the class C is a type with the lowest avoidancepriority, so that as shown in FIG. 1( a), the autonomous moving device 1cannot pass through the passage areas of the obstacles B1 and B2 otherthan the healthy person C1, and the virtual passage area 61 is set. Whenthe destination point TG is determined according to S105 in FIG. 4, theTG is set at a point at which the courses of B1 and B2 are not blockedand the change of course of C1 can be small.

When the autonomous moving device 1 moves to TG as shown in FIG. 1( b),it can be expected that B1 and B2 advance without change and C1 performsan avoidance behavior. As shown in FIG. 1(3), the autonomous movingdevice 1 can move through the passage by the avoidance behavior of C1and the autonomous moving device 1 restarts the movement to the finaldestination point.

FIG. 9 is an example of a case in which the movement of the autonomousmoving device 1 is blocked by a bed Al being transported in emergencyand nurses A2 and A3.

In FIGS. 9, A1, A2, and A3 are faster than Vmax in formula 3 and move atthe same velocity, so that A1, A2, and A3 are classified to the class A.Therefore, the passage areas of all the obstacles are impassable and thevirtual passable area 61 is as shown in FIG. 9( a). There is no virtualpassable area 61 that includes the occupied area 72 at a position atwhich the autonomous moving device 1 can stop at the maximumacceleration, so that the temporary destination point TG is set behindthe autonomous moving device 1 and the autonomous moving device 1 movesto the temporary destination point TG as shown in FIG. 9( b). In thisway, the autonomous moving device 1 can wait for passage of theobstacles at TG without affecting the movements of the obstacles. Afterall the obstacles have passed as shown in FIG. 9( c), the autonomousmoving device 1 restarts the movement to the final destination point.

FIG. 10 is an example of a case in which the movement of the autonomousmoving device 1 is blocked by the disabled person B1 and the wheelchairB2.

In FIG. 10, the disabled person B1 whose velocity is slow and thewheelchair B2 whose width is large are classified to the class B. Whenthe moving velocity of the disabled person B1 is slower, as shown inFIG. 10( a), the passage area 51B2 of the obstacle B2 other than B1 isimpassable. In the set virtual passable area 61, the temporarydestination point TG is set so that the occupied area 72 does notoverlap 51B2, and the autonomous moving device 1 moves to the temporarydestination point TG as shown in FIG. 10( b). Although it is expectedthat the course change of the disabled person B1 is difficult becausethe disabled person B1 moves along a wall, the disabled person B1 caneasily stop because the velocity of B1 is slow. If the disabled personB1 waits until the wheelchair B2 advances and a passable distance isformed between the disabled person B1 and the autonomous moving device 1as shown in FIG. 10( c), it is expected that the autonomous movingdevice 1 can pass through. When the autonomous moving device 1 can passthrough, the autonomous moving device 1 restarts the movement to thefinal destination point.

FIG. 11 is a case in which the passage through which the autonomousmoving device 1 is passing is blocked by three pedestrians.

In FIG. 11, all the pedestrians C1, C2, and C3 are classified to theclass C, so that the virtual passable area 61 is the same as thepassable area 60 as shown in FIG. 11( a). By S105 shown in FIG. 4, TG isset on the median line between the boundary lines of the passage areas51C1 and 51C2 of the pedestrians C1 and C2, and when the autonomousmoving device 1 moves to TG, it is expected that the pedestrians Cl andC2 perform an avoidance behavior as shown in FIG. 11( b). When the gapbetween the pedestrians C1 and C2 widens and the autonomous movingdevice 1 becomes able to move, the autonomous moving device 1 restartsthe movement to the final destination point as shown in FIG. 11( c).

As described above, when the way of the autonomous moving device 1 isblocked by obstacles, the autonomous moving device 1 classifies theobstacles according to the avoidance capability thereof and givesavoidance priority to each obstacle and further estimates the passageareas of the obstacles, so that the autonomous moving device 1 does notenter the passage area of a moving body whose avoidance capability islow and moves to a position at which course change of a moving body whohas high avoidance capability is small. Therefore, it is possible tosafely and efficiently avoid collision between an obstacle and theautonomous moving body.

Second Embodiment

In the present embodiment, a case in which the autonomous moving deviceincludes a computer will be described with reference to FIGS. 12 to 15.

The autonomous moving device of the present embodiment has a size onwhich a human being can ride and mainly travels outdoors. The presentembodiment is different from the first embodiment in the pointsdescribed below and the other points are the same as those of the firstembodiment, so that redundant description will be omitted. In thepresent embodiment, the same components as those in the first embodimenthave the same effects as those in the first embodiment.

FIG. 12 is a configuration diagram of the autonomous moving deviceaccording to the second embodiment.

FIG. 13 is an operation flowchart of the autonomous moving deviceaccording to the second embodiment.

FIG. 14 is a diagram for explaining a determination method of atemporary destination point TG according to the second embodiment.

FIG. 15 is a diagram for explaining a determination method of TG whenthe autonomous moving device cannot pass through a virtual passable areaaccording to the second embodiment.

In FIG. 12, a mechanical configuration diagram of an autonomous movingdevice 8 of the present embodiment is shown in FIG. 12( a) and a systemconfiguration diagram of the autonomous moving device 8 is shown in FIG.12( b). The autonomous moving device 8 includes a travel unit 81 and ariding unit 82. Although the computer is located outside in the firstembodiment, a computer 9 is included in the travel unit 81 in thepresent embodiment and a control device 814 included in the travel unit81 is wired-connected to the computer 9. Therefore, the componentstransmit and receive information to and from each other through thecommunication instruments 3 and 124 in the first embodiment can directlytransmit and receive information to and from each other by a cable.Further, the travel unit 81 includes wheels 811 to move the autonomousmoving device, drive motors 812 including encoders respectively at therear left and the rear right wheels, and a battery 813 which is a powersource in the travel unit. The riding unit 82 has an inside volume whicha human being can enter and includes a laser scanner as an environmentrecognition sensor 821.

As shown in FIG. 13, in the second embodiment, an occupied area 71 ofthe autonomous moving device 8 is represented by a rectangle whose widthwith respect to the travelling direction is r in the formula 4, so thatit is possible to estimate the distance between an obstacle and asurface of the autonomous moving device 8 according to the orientationof the autonomous moving device 8. The length of the occupied area 71 inthe front-rear direction is set based on the size of the autonomousmoving device 8 and a distance between the autonomous moving device 8and a peripheral object when the autonomous moving device 8 stops.

A travel control unit 94 controls not only the position of theautonomous moving device 8, but also the orientation of the autonomousmoving device 8 in order to easily avoid other obstacles. For example,when an angle function θgoal in the formula 1 is set so that the morethe orientation is close to a direction in parallel with the boundaryline of the passage area of the obstacle as shown in FIG. 14( a) (whenthe number of the obstacles in the virtual passable area is one) or themore the orientation is close to a direction in parallel with the medianline between boundary lines of passage areas adjacent to each other asshown in FIG. 14( b) (when the number of the obstacles in the virtualpassable area is two or more), the greater the value of the anglefunction θgoal is, it is possible to reduce the change of course ofobstacles which the autonomous moving device 8 passes.

It is assumed that the autonomous moving device 8 of the presentembodiment carries a human being, so that the width r of the occupiedarea 71 is greater than that of a human being. Therefore, when thevirtual passable area 61 is set in the same manner as in the firstembodiment, as shown in FIG. 15, the occupied area 72 may not becompletely away from the passage areas 51 of the obstacles, which areimpassable.

However, in FIG. 15 (when the virtual passable area is narrower than thewidth of the autonomous moving device), to easily understand thephenomenon, the virtual passable area 61 is shown by ignoring the widthr of the occupied area 72. When the occupied area 72 cannot becompletely away from the passage areas 51 of the obstacles, which areimpassable, impassable passage areas of the passage areas 51 of theobstacles whose class is not A are made passable one by one in ascendingorder of R, and re-setting is tried so that the occupied area 72 doesnot enter the impassable passage areas 51. If the re-setting isimpossible or if the classes of the obstacles of the impassable passageareas are only A, in the same manner as in the first embodiment, a pointwhich is located in the virtual passage area 61 behind the autonomousmoving device 8 and which is closest to the autonomous moving device 61is set to the destination point TG.

Third Embodiment

In the first and the second embodiments, as shown in FIG. 16, when thecenter lines of the current passage areas of the obstacles C1 and C2 areL1 and L2 and the center lines of passage areas of the obstacles C1 andC2 when avoiding the autonomous moving body are L1′ and L2′, if a pointwhere the angle θ1 formed by the L1 and L1′ is equal to the angle θ2formed by the L2 and L2′ is determined as TG, the temporary destinationpoint TG can reduce the change of course of both obstacles C1 and C2.

Fourth Embodiment

In the first and the second embodiments, the obstacle passage possibleareas 51 may be set according to not only the velocity and the width ofthe obstacle but also a motion pattern of the obstacle and peripheraltopography. For example, as shown in FIG. 17, if the obstacle is passingthrough a curve, a method of setting an arc-shaped passage areaaccording to the curve is considered.

Fifth Embodiment

In the first to the fourth embodiments, the travel control unit can bepreferably used as any method that can control the autonomous movingdevice under an environment in which an obstacle exists. For example, asa method of transmitting a target velocity to the control device, forexample, when the target velocity becomes lower than or equal to 0, thetravel control unit determines that it is impossible to avoid theobstacle. Further, for example, when the travel control unit generates aroute to the destination point, if the travel control unit determinesthat it is impossible to generate the route, it can be determined thatit is impossible to avoid the obstacle. Further, the travel unit can bepreferably used as a device that moves the autonomous moving device, andwheels including a steering mechanism, legs, a hover, and the like arepreferably used as the travel unit according to a surroundingenvironment.

As an environment recognition unit, which can estimate the width, theposition, and the velocity of an obstacle, various sensors using amillimeter wave, an ultrasonic wave, or the like, a pressure sensor, acommunication device that detects an IC tag or the like when an obstacleto be avoided has the IC tag or the like, or the combination of theabove components can be preferably used.

Regarding the obstacle classification unit, obstacles may be classifiedwithout performing obstacle avoidance capability evaluation by attachinga transmitter for each type of the autonomous moving device and theobstacles, receiving the type, position, velocity information, and thelike of the obstacles by a receiver attached to the autonomous movingdevice or a portion near the autonomous moving device, and transmittingthe received information to a computer. Or, the obstacles maybeclassified from the appearance of the obstacles by using a camera, a 3Dlaser scanner, or the like, which acquires the appearance. The weightmay be used instead of the width of the obstacle. When using the weight,pressure sensors are arranged under the entire floor on which theautonomous moving device travels, so that the weight of the obstacle canbe estimated from a measurement result. The avoidance priority may beset by considering the moving area of the autonomous moving device. Forexample, there is a method in which the autonomous moving device movesbased on map data, the map data has an avoidance priority setting methodfor each area, and the avoidance priority is set based on the avoidancepriority setting method.

LIST OF REFERENCE SIGNS

1 . . . Autonomous moving device of the first embodiment, 11 . . .Travel unit of the first embodiment, 111 . . . Wheel of the firstembodiment, 112 . . . Motor of the first embodiment, 12 . . . Upper bodyof the first embodiment, 121 . . . Battery of the first embodiment, 122. . . Control device of the first embodiment, 123 . . . Environmentrecognition sensor of the first embodiment, 124 . . . Communicationinstrument included in the upper body 11, 2 . . . Computer of the firstembodiment, 20 . . . Action determination unit of the first embodiment,21 . . . Information storage unit of the first embodiment, 22 . . .Travel information calculation unit of the first embodiment, 23 . . .Obstacle recognition unit of the first embodiment, 24 . . . Travelcontrol unit of the first embodiment, 25 . . . Obstacle classificationunit of the first embodiment, 26 . . . Destination point setting unit ofthe first embodiment, 3 . . . Communication instrument connected to thecomputer 2, 51 . . . Passage area, 60 . . . Passable area, 61 . . .Virtual passable area, 71 . . . Shortest stop position of the autonomousmoving device, 72 . . . Occupied area of the autonomous moving device, 8. . . Autonomous moving device of the second embodiment, 81 . . . Travelunit of the second embodiment, 811 . . . Wheel of the second embodiment,812 . . . Motor of the second embodiment, 813 . . . Battery of thesecond embodiment, 814 . . . Control device of the second embodiment, 82. . . Riding unit of the second embodiment, 821 . . . Environmentrecognition sensor of the second embodiment, 9 . . . Computer of thesecond embodiment, 91 . . . Information storage unit of the secondembodiment, 92 . . . Travel information calculation unit of the secondembodiment, 93 . . . Obstacle recognition unit of the second embodiment,94 . . . Travel control unit of the second embodiment, 95 . . . Obstacleclassification unit of the second embodiment, 96 . . . Destination pointsetting unit of the second embodiment, Oi, Ai, Bi, Ci . . . ithobstacle, Li . . . Boundary line of ith virtual passable area 61, Ljk .. . Median line between boundary lines of jth passage area 51 and kthpassage area adjacent to each other, TG . . . Temporary destinationpoint

1. An autonomous moving device comprising: a travel unit including awheel driven by a motor; and an upper body including an environmentrecognition sensor that detects an obstacle in a traveling direction,wherein the upper body includes: a means for recognizing a position ofthe autonomous moving device and an obstacle; a means for evaluatingavoidance capability of the obstacle, a means for determining capabilityof avoidance of collision with the obstacle; and a means for obtainingpriority of collision avoidance of an estimated passage area of theobstacle from the capability of avoidance of collision, and the upperbody further includes: a control unit that moves the travel unit to arange which is an area where an estimated passage area of an obstaclewhose priority of collision avoidance is high does not overlap an areawhere the travel unit is located and which is an area where collisioncan be avoided even if an area where an estimated passage area of anobstacle whose priority of collision avoidance is low overlaps the areawhere the travel unit is located.
 2. The autonomous moving deviceaccording to claim 1, wherein the means for evaluating avoidancecapability quantitatively calculates the avoidance capability from avelocity and a width of the obstacle.
 3. The autonomous moving deviceaccording to claim 1, wherein the means for evaluating avoidancecapability sets avoidance priority of the obstacle whose avoidancecapability is lower than a reference value to be high.
 4. The autonomousmoving device according to claim 1, wherein the means for evaluatingavoidance capability sets avoidance priority of an obstacle whosevelocity is slower than a reference range and an obstacle whose velocityis faster than the reference range to be high.
 5. The autonomous movingdevice according to claim 1, wherein the means for evaluating avoidancecapability classifies the obstacle into several types on the basis ofavoidance capability.
 6. A control method of an autonomous moving deviceincluding a communication device that communicates with a computerincluding an information storage unit, a travel information calculationunit, an obstacle recognition unit, a travel control unit, an obstacleclassification unit, a destination point setting unit, and an actiondetermination unit, the control method comprising: determining thepresence or absence of information from the obstacle classificationunit; transmitting a final destination point in the information storageunit to the travel control unit as a current destination point when noinformation is transmitted from the obstacle classification unit;obtaining a passable area in which the autonomous moving device cantravel without colliding with an obstacle by a travel unit wheninformation is transmitted from the obstacle classification unit;estimating a passage area of a currently captured obstacle; setting avirtual passable area which is an area virtually set to be passable forthe sake of calculation; and determining a destination point based onthe virtual passable area.